Internal combustion engines include exhaust control mechanisms for controlling the flow of exhaust from each combustion chamber of the engine. In most instances, these mechanisms comprise valves.
In those instances where the engine operates on a two-stroke or two-cycle principal, the valve is often of the sliding or rotating type. Generally, this type of valve does not serve to ever completely close the opening or port in the combustion chamber wall or the exhaust passage. Instead, the valve moves between a first position in which the valve does not obstruct or obstructs very little of the exhaust port, and a second position in which the valve partly obstructs the port. Because the sliding or rotating type valve can partially obstruct the exhaust passage, it can be used to control the timing of the exhaust flow, and thus the performance or running conditions of the engine.
The sliding or rotating type valve, however, suffers partly in its reliability. Because these valves have a relatively small range of movement and are not continuously moved, they may seize within the guide in which they are mounted. Providing lubricant to the valve reduces this problem somewhat, but suffers from the attendant problem that the high temperature of the engine may reduce the lubricant into carbon deposits on the valve, causing the valve to seize.
An exhaust control for an engine of the type utilized to power a watercraft which is reliable and easy to maintain is desired.